CRON 2>&1 >/dev/null vs >/dev/null 2>&1

Question

I just created a tiny shell script to be run every minute.

What happened was that it started flooding my mail.

$ crontab -l
* * * * * /home/user/bin/test 2>&1 >/dev/null

I changed the redirection to >/dev/null 2>&1, and it stopped.

I thought 2>&1 >/dev/null and >/dev/null 2>&1 are equal in shell at least... Now I hesitate, are they (equal) and it's just the CRON programmed this way?

See Order of redirections (although be aware that cronjobs are more likely to be run in /bin/sh than bash). — steeldriver, Feb 23 '22 at 00:33

score 1 · Answer 1 · edited Feb 23 '22 at 08:37

1

Those two commands are not the same.

1>stdout filename must be located in between the command and 2>&1

$ command  1>  stdoutput_filename  2>&1

2> => redirect stderr, &1 => means stdoutput_filename.

$ command 2>&1 > /dev/null => &1 does not mean /dev/null

Example

$ ls issue issue.net nofile 2>&1 > /tmp/testfile

ls: cannot access nofile: No such file or directory

$ cat /tmp/testfile
issue
issue.net

$ ls issue issue.net nofile 1> /tmp/testfile 2>&1

$ cat /tmp/testfile
ls: cannot access nofile: No such file or directory
issue
issue.net

edited Feb 23 '22 at 08:37

Vlastimil Burián

28,462

answered Feb 23 '22 at 02:02

firstcolor

11

1

It doesn't have to between the two, it just has to before 2>&1. It can be before the command. – muru Feb 23 '22 at 11:51

CRON 2>&1 >/dev/null vs >/dev/null 2>&1

1 Answers1

Example